The heating element in an electric oven is either "on" or "off". When the thermostat senses that the oven temperature is too low, it turns on the heating element and re-heats the oven. Electric ovens typically have a temperature swing to them due to this cycling on and off and don't maintain a constant temperature.

Commercial gas ovens have a "by-pass" feature that allows the flame to be set to low thus providing precise temperature control. No temperature swing with gas.

Very good description Steve. A gas oven holds a much more precisely constant temperature. That's why almost every professional cook uses a gas fired oven.

Electric ovens just don't have the temperature control needed. Electrical oventop flames also continue to give off heat when turned off. When you turn off an oventop flame fired by gas, it's off.....No chance of burning your pots or pans or their contents.

The time I lived in New York (Till 1982) I remember that almost all Pizza Bakers also used gas fired Pizza ovens.